Susanna Phelps Gage 443 



Fig. 16. A photograph (X47io) of Sec. 192, through the neuropore to 

 show: The point of most intimate union of the thickened epidermis with 

 the neural epithelium (for the extent of the neuroporic thickening, (of. Figs. 

 1-8) ; the total folds entering into the formation of the visual lobe; the 

 sharp angle formed by the albicantial furrow at the right; the external 

 filling up of this angle at the left, indicating its independent ending (see 

 text) ; the mesoderm continuous over the eye-vesicle, but interrupted at the 

 neuropore (cf. Fig. 4). The cilia present in this section do not show clearly 

 here. 



Fig. 17. Ventral view of a large model of the nephric region of Homo 

 148, extending from Sec. 94 to Sec. 295 (X 75). It shows the two Wolffian 

 ridges, each including the pronephric remnant; the mesonephros; the dorsal 

 portion of the mesentery; a part of the stomach and lesser peritoneal cavity; 

 the union of the allantoic stalk with the intestine; the cloaca and the 

 imperforate anal plate; the right Wolffian duct and its union with the cloaca. 



The opening of the pronephric tubules (Fig. 18) on the ccelomic surface is 

 shown. Crosses indicate the position of the first eight mesonephric tubules 

 which do not open on the coelomic surface (Fig. 19) but connect with the 

 Wolffian duct. The 9th to the 20th tubules have no connection with the 

 WolflSan duct. The 9th and the 13th to the 18th are open to the ccelom. 

 The 10th to the 12th are hollow but connect neither with duct nor ccelom. 

 The 19th to the 21st are thickenings touching the ccelomic epithelium but 

 showing no cavity. The general arrangement of the tubules of the other 

 side is similar but not identical. 



The slight furrows at the cephalic end may represent a rudiment of the 

 supra-renal or adrenal body. 



Fig. 18. From a photograph (X 160) of Sec. 104, Homo 148, showing the 

 pronephric tubule of the right side (Fig. 17) with its opening into the 

 ccelom and its duct traceable for a few sections farther cephalad. The 

 cardinal vein is also seen. 



Fig. 19. From a photograph (X 160) of Sec. 166 through the 7th meso- 

 nephric tubule of the right side (Fig. 17), showing the small rudiment of the 

 glomerulus; the typical S-shaped tubule connecting with the Wolffian duct 

 and thin-walled Bowman's capsule which a few sections farther caudad unites 

 with the ccelomic epithelium and forms a small opening. The remainder of 

 the first eight tubules are of this same general type but are completely 

 separated from the ccelomic epithelium. 



Fig. 20. From a photograph (X 160) of Sec. 195, through the 10th meso- 

 nephric tubule of the left side (Fig. 17), showing a wide opening to the ccelom 

 and its independence of the Wolffian duct. 



The photographs reproduced on this plate were made by Henry Phelps 

 Gage and are part of a complete series of 96 taken from the sections. 



